Apparatus for pumping wells



APPARATUS FOR PUMPING WELLS Filed March 25', 1932 //v I/E/VTORS IPatented Dec. 15, 1936 UNITED STATES APPARATUS FOR PUIVIPING WELLSIrving 0. Harris, Milwaukee, Wis., and Harry W. Doubrava, Beverly Hills,Calif.

Application March 25, 1932, Serial No. 603,114

9 Claims.

This invention relates to pumping methods used in pumping fluids fromdeep holes in the earth, as from wells drilled for petroleum.

The deep lying formations from which petroleum is obtained, contain gasmixed with the oil and under high pressure. When the wells are firstcompletechthe gas pressure usually brings the oil to the surface of theground; and the wells flow oil and gas for a period of time, afterwhich, the gas pressure is not sufficient to bring the oil to thesurface; and then it is necessary to use other methods to lift the oilto the surface of the ground. Quite satisfactory results have beenobtained with the various methods heretofore used as long as the liftfrom the level to which the gas brings the oil to the surface of theground is not excessive.

Of late years, wells by the hundreds have been drilled to depths of from4000 to 8000 feet; and such wells produce oil for a limited time withoutpumping. For a considerable time after the gas pressure has ceased to besufiicient to bring the oil to the surface of the ground, it stillbrings the oil a large part of the way; and various methods are usedwith success in bringing the oil to the surface by assisting the gaspressure. As the gas pressure declines, the difliculties of liftingoilby means of the sucker-rod pumps and various other methods used,increase until a point is reached where abandonment follows due to theinability of pumping from 4000 ,to 8000 foot depths without theassistance of the virgin gas pressure in the wells.

Most of the deep wells are quite crooked and 35 the casings small; andthe mechanical troubles and maintenance expense with sucker-rod pumpsare very severe. Many air and gas lift systems have objectionablefeatures and hazards due to their producing surges or severeand suddenchanges in pressure between the inside and the outside of the wellcasing, and due to the application of excessive pressure tending todrive the oil back into the oil-bearing formations.

It is an object of our invention to provide a means of lifting oil fromthe bottom of wells of any depth without dependence upon the liftingeifect ofthe gas within the oil-bearing structure, withouttheapplication of back-pressure to the oil structure while pumping, andwithout submitting the wells and their casings to severe, sudden andharmful changes in pressure.

It is an object of our invention to provide a means of pumping from thebottom ofa well after the virgin pressure has been depleted to a pointwhere the gas pressure will not lift the 911 above the top of theoil-bearing formation and the oil enters the well by gravity seepage andslight residual gas pressure, or as the result of re-pressuringoperations.

Another object is to provide a system of pumping in which the apparatusinstalled within the well is of maximum simplicity and reliability andsuch as to produce a minimum of wear and hazard of damage to the casingof the well and the formation surrounding it.

Another object is to provide a system of pumping in which oil and gasare used under conditions permitting high economy and a minimum ofwastage of oil and gas.

We attain the objects of this invention by the means illustrated in theaccompanying drawing, in which, Fig. 1 is a section through the axisofthe portion of the mechanism installed in the well, and a schematicdiagram of the apparatus connected to and operable with that installedin the well, and Fig. 2 is a view of a nozzle sleeve.

The string of pipe or tubing l in Fig. 1, is the outer tubing, which isinstalled in the well and supported at the casing head. A machinedshoulder is provided at the lower end, as indicated at 4, and machinedseats against which the packings indicated at 5, 6, and I bear, forreceiving the mechanism installed within the tubing l. The

shoulder 4 prevents the mechanism from passing beyond the end of thetubing 8.

A string of pipe, or tubing, designated the intermediate tubing- 3, isinstalled within the outer tubing and supported by supporting means atthe casing head. Attached at the lower end of the intermediate tubing isan assembly of parts, the enclosing housing of which is indicated atIll. The packings indicated at 5, 6, and I make fluid-tight contact withthe outer tubing.

Installed within the intermediate tubing 3 is an assembly of tubing androdsections, indicated at 2, forming the inner tubing, orgas-dischargeline. The said assembly is suspended at the derrick by amechanism including rod I8, packing l1, lever l9, walking-beam 5, andcounterweight 20 in such a way that the inner tubing may be reciprocatedvertically through a short distance by actuating cylinder 2|, which iscontrolled by timing and control mechanism 22. Cylinder 22 may beactuated by oil pressure from the oilpump 23; and thisoil may beexhausted into the oil-tank and gas-trap 25. The inner tubing connectswith the housing H) by means of telescopic Joint including packings l0.

Connected into the string of inner tube sections 2, or thegas-discharge-line, are valves of a checkvalve type permitting flow offluid from the gasdischarge-line into the space between thegasdischarge-line 2 and the intermediate tubing 3, when the relativepressures permit, but not in the reverse direction. Two of these valvesare indicated at 68 in Fig. 1. One or more of these valves may be used.When two or more are used, they are placed at intervals at differentelevations between the mechanism in the housing Ill and the groundlevel.

A gas compressor, or its equivalent in the way of a connection to apipeline system connecting with a central compressor plant, is indicatedat 65; and 23 represents an oil-pump, 24 a second compressor, orequivalent, 25 a gas-trap including an oil-tank with a small oil storagecapacity, and 28 is a mixer.

In operation, oil-pump 23 draws oil from the gas-trap and oil-tank 25and delivers it at the required pressure at the mixer 28; and the gascompressor 24 takes gas from the gas-trap and from compressor 65 andcompresses it to the required pressure and delivers it to the mixer 28.The flows of the fluids are shown by arrows. The oil and gas are mixedin proper proportion at mixer 28; and the mixture is forced down thespace between the outer tubing I and the intermediate tubing 3, asindicated by the arrows, and through the passageways in the housing l0and into the separator chamber 33 through nozzles 32.

A portion of the gas is separated from the oil in separator chamber 33and used through displacement chamber 40, as hereinafter described; andthe gas not thus separated and used, and all of the oil, plus the virginoil pumped and injected into the stream at 35, as hereinafter described,passes upward through the passageway in housing In, indicated at 35, 36,and H, and in the space between the intermediate and inner tubings, asindicated by the arrows, and out at outlet 30, whence the mixture of gasand oil goes to the gas-trap and oil-tank 25, where the gas and oil areseparated, a part of the oil going to the oil-pump 23 again, and the gasgoing to the compressor 24 again, thus completing the circuit. The gasseparated out at the separator 33 and used through the displacementchamber, as herein described, passes upward between the outer casing andthe well casing and out at outlet 29, where it is led to compressor 65and compressed and delivered to the connection between the gas-trap andcompressor 24 at the pressure maintained at that point, thus completingthe circuit for that part of the original quantity of gas. The increaseof oil due to the virgin oil pumped and injected at 36, as described, istaken out of the circuit at outlet 44; and any excess of gas due tovirgin gas coming in with virgin oil, or any deficiency of gas due tolosses, is equalized by withdrawal from or injection into the circuit at21 by means not shown. The oil-pump and compressors are adjusted tooperate at the pressure and rates of delivery of fluid required tomaintain the circulation described.

The descending and ascending columns of fluid balance each other exceptfor the difference in weight due to the different amounts of gascontained in the two. The pressures supplied by the oil-pump andcompressors are required to be high enough to overcome the stateddifference in weight and to do the work required to overcome thefriction and slippage losses and maintain the circulations. Thesepressures are small compared with the pressures existing at the bottomof the circuit. The gas enters the circuit at mixer 28 at a certainpressure and is compressed as it descends to the bottom with the oiluntil, at the bottom of the circuit, it has a pressure several times thepressure at which it enters the circuit. The pressure in chamber 33 isthat due to the weight of the column of liquid and gas in the descendingcolumn between the tubings I and 3, plus the initial pressure at 28,minus friction losses. It is, also, equal to that due to the weight ofliquid and gas in the ascending column within tubing 3, plus and backpressure at 25, plus friction losses. The apparatus thus operated actsas a high-pressure, hydro-pneumatic compressor, delivering high-pressuregas at the bottom of the circuit.

The mixture of oil and gas passes from the inner tubing into themechanism at the bottom through nozzles 32, by means of which, themixture is directed in a spiral direction down the outer cylindricalwall of the separator chamber 33, causing a whirling or vortex movementwithin the chamber which separates the gas and oil, the oil going to theoutside and the gas to the center on account of the large difference inthe specific gravities of the two fluids. A portion of the separated gasgoes toward the center and to the top of the separator chamber and istaken out at outlet 34, as hereinafter described. The remainder of thegas and all of the oil passes out of the chamber at outlet 35 through aduct between 35 and 36, which is made of small cross-sectional area soas to produce a desired drop in pressure between 35 and 36, and flowsupward from the end of the duct at 36 in the passageway H and to thesurface of the ground in the space between the inner and intermediatetubings, and thence into the gas-trap 25.

In the lower part of the mechanism at the bottom of the well is adisplacement chamber 40, which is operated in somewhat the same manneras the usual displacement chamber, air-lift pump. Parts 4| and 42 arevalves controlling oil and 46, 41, 60, and 69 are valves controllinggas. The valves 46, 41, and 66 are operated in proper sequence andtiming by the reciprocating movement of the inner tubing 2, aspreviously described, through the medium of cams 48, 49, and 6|, springs58, 59, and 66, and bell-cranks 50, 5|, and 62, respectively. Valve 69is a check-valve to prevent reverse flow through valve 60.

Valves 46, 41, and 60 are held in the closed position against the valveseats by the springs 58, 59, and 66, respectively, and are opened whenthe bell-cranks 50, 5|, and 62, engaging the respective valve stems, areactuated by riding up on the cams 28, 49, and 6|, respectively, insequence. Valve 46 is shown in the open position and valves 4'! and 60in the closed position in the drawing.

When the inner tubing 2, with the attached cams is moved axially anamount sufiicient to cause bell crank 50 to ride down cam 48 under thepressure of spring 58, valve 46 is closed. When the axial movement hasprogressed enough to cause bell crank 62 to ride up on cam 6|, valve 60is opened, valves 46 and 41 remaining closed. This is the secondposition in a sequence, the position in which valve 46 is open andvalves 60 and 1 closed being the first. A further movement of the innertubing 2 with the attached cams causes valve 4'! to be opened by bellcrank 5| riding up on cam 49, valves 46 and 60 still remaining open.This is the third position in the sequence. Travel of the inner tubing 2with the attached cams in a reverse direction to the position ofstarting, as described above, with valve 46 open and valves 60 and 41closed, completes the cycle. The three valves 46, 60 and 41 may beoperated in the desired sequence and with pauses of the desired lengthin the three positions described by proper proportioning of the cams andthe mechanism for reciprocating the inner tubing. The mechanism forreciprocating the inner tubing is no part of the present invention andis not detailed.

When the inner tubing and the attached cams are in a'position such thatvalve 46 is open and valves 41 and 60 are closed, the displacementchamber 40 is connected to the separator chamber 33 through passageway34 and isolated from the well. When thus conntwted andwhenthecirculation of the mixture of gas and oil is operative, the pressurein the separator chamber 33, due to the difference in weight between gasin passageway 34 and oil and gas in the passageway between 35 and 36 andbetween the levelsof the liquid in the two chambers, and, also, due tothe drop in pressure between 35 and 36 caused by the small size of thepassageway, as previously described, is higher than the pressure in thedisplacement chamber. The pressure in the displacement chamber 40 whenvalve 42 is open and liquid is being forced out of the chamber throughvalve 42 and tubing 3 to the gas-trap 25, is fixed by the pressuremaintained in the gas-trap 25 and the conditions of flow and pressure inthe column of fluid between chamber 40 and gas-trap 25. The pressureexerted by pump 23 and compressor 24 is made high enough to force acirculation of fluid through separator chamber 33, as described; and thepressure in chamber 33 is made higher than the pressure in chamber 40 bypurposely making a friction drop of a desired amount in the passagewaybetween 35 and 36. The pressure in chamber 33 being higher than thepressure in chamber 40, the gas must flow from chamber 33 into chamber40 and displace the liquid in chamber 40.

The relationships of pressure and the resulting flows may be morereadily observed from a study of the diagrammatic representation of theapparatus shown in Fig. 2, in which the relationships of pressure areindicated by the relative position of the different parts in the figure.Pump 23 and compressor 24 receive fluid from the gas-trap 25 and createand maintain' the pressure at 28 at the necessary value to force thecirculation. Compressor 65 receives gas from the well at low pressureand delivers it at the pressure maintained in gas-trap 25. With theserelationships properly adjusted, the circulations of fluid indicatedbythe arrows and described herein must follow in accordance with thenatural laws governing the flow of liquids and gases. The eiiect andpurpose of this is to cause gas, separated from the oil in the separatorchamber, as described, to flow through the passageway 34 and valve 46into the displacement chamber 46 and displace any oil in the chamber andcause it to open the check-valve 42 and pass out into he stream of gasand oil ascending from the separator in the passageway at 36.

When the displacement chamber 4i!v is filled with gas and the innertubing and its attached cams are moved axially with reference to thehousing l0 and sliding through packings 10, to such a position as toclose valve 46 and open valve 60, valve 41 remaining closed, the gas indisplacement chamber 40 will flow into the inner tubing, orgas-discharge-line, through valve 60, and raise the pressure in thatline to values higher than the pressures in the space between the innerand intermediate tubings and open the valves 63,

, discharge-line.

which are placed at intervals in the lower onehalf to three-quarters, ormore, of the length of the gas-discharge-line, and allow gas to flowfrom the gas-discharge-line into the outer space as long as the pressureremains higher in the gas- As the pressure falls, the valves 66 willclose in succession, beginning with the lower one; and the pressure inthe displacement chamber and the gas-discharge-line will fall until itequals the pressure in the space between the inner and intermediatetubings at the elevation of the uppermost valve 68. The valves 68 willprevent any reverse flow.

When the pressure in the displacement chamber has been reduced asdescribed and the inner tubing and its attached cams are moved so as toopen valve 41, valve 60 remaining open and valve 69, automaticallyclosing to prevent reverse flow through it and valve 60, valve 46remaining closed, the gas remaining in displacement chamber 40discharges through valve 41 and outlet 54 into the well in the spacebetween the outer tubing and the well casing; and oil from the wellopens the foot-valve 4| and passes into the displacement chamber 40through inlet 61, valve 4|, and passageway 43.

When the displacement chamber is full of oil and the inner tubing andits attached cams are moved to a position so as to close valves 41 and60 and open valve 46, gas from the separator chamber 33 flows into thedisplacement chamber and displaces and forces the new charge of virginoil into the circulation of oil and gas as previously described, thuscompleting the cycle of operation of the displacement chamber.

From the foregoing description, it will appear that the virgin oil isinjected into the circulating flow of oil and gas mixture maintained bythe oil-pump and compressors, as previously described, by adisplacement, or airvlock, method in which the gas at the pressureexisting at the bottom of the circuit is exchanged for an approximatelyequal volume of virgin oil. After being injected into the circuit at thebottom, the virgin oil is brought to the surface of the ground by thecirculation of the mixture. When the exchange of gas for oil is beingmade, there is no volumetric change or change of pressure in the,

circulation circuit but a change in the relative amount and distributionof gas and oil. Gas is the bottom of the circuit and at the pressureexisting there, for an equal quantity of oil, a large portion of thegas, measured at atmospheric pressure, is recovered and returned to thecircu lation circuit higher up and at a lower pressure through thevalves 68, as previously described. Only that remaining in thedisplacement chamber after the pressure has been lowered to that in theascending column of mixture at the uppermost valve 68, is dischargedinto the well, and must expand to atmospheric pressure, from which ithas to be re-compressed by compressor 66 and returned to the circuit atthe pressure of the inlot of compressor 24. v

' The system appears to be quite intricate; but a graphical andmathematical analysis of its operating characteristics shows that, whileits various circulation circuits are intermeshed and inter-related sothat a change in one'circuit affeats all of the others, it isnevertheless largely self-regulatory and simple of adjustment and inoperation. When the pressures and flows of gas and oil are adjusted atmixer 28, the various portions of the circulation system below ground,due to the inter-relationship and inter-meshing, adjust themselves tothe values corresponding to the adjustment of pressures and flows andthe timing of the gear of the displacement chamber.

Attention is called to the fact that, in addition to supplying highpressure gas for the operation of the displacement chamber and carryingout the virgin oil after its injection into the circuit, the circulationsystem described decreases the hydrostatic pressure to be handledthroughout the system in proportion to the ratio of the amount of gasand oil in the ascending column of fluid. If there is 35% of gas, thehydrostatic pressure in the separator chamber is only a little over 65%of the pressure corresponding to a column of solid oil from that pointto the surface of the ground. The gas in the circulation circuit whichis recompressed by compressor 24 is never at a pressure less than thepressure in 25, which is of the order of from 100 to 300 pounds persquare inch. There is a large saving of energy required forrecompression because of the well known fact that it takes far lessenergy to compress, for example, from 200 pounds to 400 pounds persquare inch than it does to compress from atmospheric pressure to 200pounds. Likewise there is a saving due to the fact that there is asmaller slippage between gas and liquid at pressures ranging from 200pounds per square inch upward than between atmospheric pressure and 200pounds per square inch, with a consequent advantage in the liftingeffect due to the gas in the ascending column of mixture. The recoveryof a considerable portion of the gas from the displacement chamber andits injection into the ascending column of mixture where it assists inlightening the pressures and in lifting the liquid, produces asubstantial saving of energy. The combined efiect of these savings andadvantages makes it possible to bring to the ground surface a barrel ofliquid with a much smaller number of cubic feet of free gas and a muchsmaller expenditure of energy for compressing the gas and circulatingthe mixture than is possible with other methods of gas-lift ordisplacement gas-lift.

In addition to these advantages resulting from the use of the liquid andgas circulation, hydropneumatic compression, and centrifugal separation,it is pointed out that a large number of wells, each requiring differentpressures at the displacement chamber due to difierent depths of pumpingand different production, may be served by one central compressor plantoperating at a fixed pressure. The hydropneumatic compression stage ineach well makes the necessary adjustment of pressures without loss ofenergy and makes it possible to deliver gas at, for example, 2000 poundsper square inch pressure at the displacement chamber with not over 700pounds per square inch at the compressor above ground. Otherdisplacement gas-lift methods require either the high pressure to bedelivered by a mechanical compressor or a very large volume of gas witha slug-flow method. In either case, the quantity of free air and totalenergy required exceed the amounts required by this method.

Attention is called to the fact that, with this system, the highpressure gas employed in the lifting operation is entirely isolated fromthe well and oil-bearing structures at all times. When the displacementchamber discharges its gas into the well, it is in relatively smallvolume, and it passes upward between the well casing and the outertubing to the outlet 29 where it goes to the suction of the compressor,the pressure being maintained at atmospheric pressure, or lower ifdesired. Thus no back pressure is applied to the oil structure, thusfulfilling one of the important objects of the invention.

Attention is called to the fact that, since the displacement chamber andits oil inlet valve may be placed very near the bottom of the well ifneeded, since the operation of the system does not depend upon anycondition in the well external to the mechanism, such as gas pressure ordeep submersion, excepting submersion sufficient to cause the oil in thewell to open the foot-valve 4| and flow in and fill the displacementchamber, and that since the operation of the displacement chamber ispositive and can be made to operate at any depth, it is possible withthis system to pump oil from the bottom of wells of any depth, thusfulfilling one of the important objects of the invention.

Attention is called to the fact that, since the operation of the systemis started without any rocking or pulsation of the fluid in the well,and since, in operation, the amount of the intermittent withdrawal ofoil from the well is limited to the capacity of the displacementchamber, this system does not produce any detrimental surges or suddenchanges of pressure that might be destructive to the casing or oilstructure around the hole, thus fulfilling one of the important obiectsof the invention.

Attention is called to the fact that, since the required submersion ofthe displacement chamber is small and usually less than the penetrationof the well bore below the top of the oilbearing formation, it ispossible to pump oil from the well after the virgin gas has beendepleted so that the oil does not rise above the level of its entry intothe well, thus fulfilling another of the objects of the invention.

It is pointed out that, with this method, all of its operations arewithin closed circuits from which losses of liquid and gas are verysmall, if present at all. There are but two external outlets aboveground, outlet from which the output of oil is withdrawn, and outlet 21into which gas to supply losses may be introduced or where gas may bedischarged in those cases where the well itself makes more gas thanneeded in the system. In wells that have considerable gas pressure whichforces the oil level above the oilbearing formation, the apparatus isinstalled no a deeper than necessary to maintain-the required submersionof the displacement chamber" at all times. When the oil level haslowered below the range of the apparatus as installed, it is lowered bylengthening the tubing lines and adjusting the pressures to suit thechanged conditions. Thus it will be seen that any work done by any gaspressure within the oil-bearing structure tending to lift the oil, isutilized when present; but it is not essential to the operation of themethod of pumping. Furthermore, all gas coming from the well is saved.In most cases, the gas compressor is located in a central plantsupplying a group of wells; and the gas coming from the wells is passedthrough a plant which removes any gasoline carried by it, after which,it enters the circulation again to acquire more gasoline. The intimatemixture of the gas and oil, the repeated hydraulic compression anddecompression of the gas, and the long travel in intimate mixture inmaking several circuits of the system before going to the plant whichremoves the gasoline, will produce maximum absorption of gasoline. Thusit will appear that this method meets the object of the invention as tooperation under conditions of economy and with a minimum of wastage ofoil and gas.

The combination of parts and the method of operation hereinbeforedescribed are to be used in wells in which the virgin gas has beendepleted and the fluid level lowered to such a point that thehydrostatic pressure of a column of v oil of a height equal to thedistance from the fluid level to the ground surface is greater than themaximum delivery pressure of compressor 24 above atmospheric pressure;and this combination and the stated method may be used when the statedhydrostatic pressure is of any value up to several times the maximumdelivery pressure of compressor 24. Before the fluid level has loweredto a stage of this order, the same equipment may be used and a modifiedmode of operation employed to pump the oil from the well, in which theoutlet 35 from the separator 33 is plugged, the oil-pump is disconnectedand nothing but gas is forced downward in the space between the tubingsI and 2. Except for the elimination of the oil circulation and,consequently, the separating action of the separator 33, the mode ofoperation is the same as hereinbefore described.

The system is very flexible and capable of modification to suit thelarge range of conditions to be encountered in the oil fields, both asto the condition and history of the wells and as to the equipment in useprior to the installation of the new system and to be associated withit. The system may be operated with all of its component parts in use orwith some of those described eliminated, and the combinations altered tosuit special conditions, as, for instance, operating without using agas-discharge-line and using areciprocating movement of one of the otherstrings of tubing for the operation of the valves, or' using an entirelydifferent method of operating the valves either with or without using agas-disoharge-line.

In the specific embodiment of the invention used as an illustrativeexample, a displacement chamber is used as a means of drawing liquidfrom the well and discharging it into the conduit through which it islifted to the ground level. No specific form of chamber is necessary noris a displacement chamber an essential detail of the invention. Anyequivalent displacement means will function in combination with theother elements. The essential requirementfor the displacement meansincluded as an element of the invention is that it draw liquid from thewell into a receptacle, represented by the displacement chamber in theillustrative example, and that the liquid be positively displaced andforced out of the said receptacle by a means actuated either wholly orpartly by gas pressure, the displacement of the liquid beingaccomplished either directly by the gas itself or through anintermediary means or equivalent, and the gas thus used by thedisplacement means being, also, employed. either before or after use inthe displacement means, or both before and after, in aerating orlightening the columns of liquid in the conduit system, either method,the long lines of the tubing are not sub- .iected to large alternationsof stress, as is the case with sucker-rod pumps where the weight of theentire column of fluid filling the oil-tubing is transferred from therod to the tubing and back to the rod again at each stroke; hence thereis no appreciable wear of the tubing and well casing due to theelongation and return due to the alternating changes in stress which, inthe case of the sucker-rod pumps, increase from nothing at the topprogressively with depth to a maximum of several inches at the bottom.With our system, the movement of the inner tubing, or gasand thevariation of stress is very slight.

While we have shown and described specific embodiments of the invention,we do not limit ourselves to the exact details of construction disclosedbut may employ such changes in construction and arrangement of parts,and such modifications and equivalents as come within the scope of theappended claims- We claim:

1. In apparatus for pumping wells, strings of tubing, installed in awell; connecting means adapted to provide, in combination with the saidstrings of tubing, conduitsfor the conveyance of a descending flow offluid from the upper end of the strings of tubing to the lower end ofthe same and an ascending flow of fluid from the lower end to the upperend of the said strings of. tubing; a gas-discharge-line, comprising astring of tubing extending from a point near the lower ends of thestrings of tubing first above named and extending upward toward theground level; means for supporting the gas-discharge-line and actuatingand timing a reciprocating movement of the same; valves providingcommunication between the gas-disoharge-line and one of the conduitsaforesaid in a manner to permit flow of fluid from thegas-discharge-line into the conduit but not in the reverse direction; adisplacement chamber near the lower ends of the strings .of. tubing andthe gas-discharge-line; means for supplying gas to the displacementchamber; valves adapted to be actuated by the stated reciprocation ofthe gas-discharge-line and to permit flow of fluid between the. saidmeans for supplying gas and the displacement chamber, between thedisplacement chamber and the gasdischarge-line, and between thedisplacement chamber and the space without the apparatus in the well insequence; valves permitting flow of fluid in one direction only from thespace in the well external to the apparatus in the well into thedisplacement chamber and between the latter and the conduit conveyingthe ascending flow of fluid first above described; means for maintaininga circulation of fluid through the conduits for the conveyance of thedescending and ascending flows of fluid first above described; and meansfor maintaining the required amounts of fluid in the conduits anddischarging any increase'of fluid therefrom.

2. In apparatus for pumping wells, strings of tubing in concentricassembly, installed in a well; connecting means adapted to provide, incombination with the said strings of tubing, conduits for conveying aflow of fluid downward in one conduit from the upper end of the stringsof tubing to the lower end of the same'and in the reverse direction inanother conduit; a gas-discharge-line, situated concentrically withinthe inner of. the strings of-tubing above named and comprising a stringof tubing sections, supporting rod sections, and valves at intervalsbetween the tubing sections, the gas-discharge-line being connected tothe conduits aforesaid near their lower ends and extending upward fromthe same and being adapted to have a reciprocating movement, the saidvalves being adapted to allow flow of fluid from the gas-discharge-lineinto one of the conduits surrounding it but not'in the reversedirection; means for supporting the gas-discharge-line at the groundlevel and of actuating and timing a reciprocating movement of the same;a displacement chamber near the lower end of the strings of tubing andmeans for supplying gas to the displacement chamber; valves adapted tobe actuated by the stated reciprocating movement of. thegas-discharge-line and to control the filling of the displacementchamber with gas and the emptying of the same; valves allowing flow offluid in one direction only between the space in the well external tothe apparatus in the well and between the displacement chamber and theconduit which conveys the fluid upward to the ground level as firstabove described; and means for maintaining flow of fluid through theconduits and of discharging increase of fluid above ground.

3. In apparatus for pumping wells, two strings of tubing in concentricassembly, installed in a well; a housing providing a structuralconnection between the two strings of tubing at their lower ends andpassageways providing, in combination with the strings of tubing,conduits for conveying a flow of fluid downward in one conduit andupward in another between the said housing and the upper ends of thestrings of tubing; a gas-discharge-line concentrically within one of thestrings of tubing and comprising a string of tube sections extendingfrom a connection with the said housing upward toward the upper end ofthe strings of tubing aforesaid and adapted to have a limitedreciprocatory movement axially with reference to the housing; valvemeans for allowing flow of fluid from the gasdischarge-line into one ofthe conduits but not in the reverse direction; an extension of thegasdischarge-line into and a valve actuating mechanism within thehousing; means for supporting the gas-discharge-line at the upper endthereof and of actuating and timing the reciprocatory movementaforesaid; a displacement chamber within the housing; means forsupplying gas to the displacement chamber; valve means adapted to beactuated by the valve actuating mechanism aforesaid and thereciprocatory movement of the gas-discharge-line and to control thefilling of the displacement chamber with gas and the emptying of thesame in alternation; means for admitting liquid from the well into thedisplacement chamber and from the said chamber into the conduitsaforesaid, the said means including valves for preventing flow in thereverse direction; and means for maintaining flow of fluid through theconduits and for discharging excess of fluid above ground.

4. In apparatus for pumping wells, an assembly of strings of tubing,installed in a well; means of communication between the lower ends ofthe strings of tubing forming, in combination therewith, conduits forconveying a flow of fluid downward from the upper end to the lower endand.

back to the upper end of the assembly; a gasdischarge-line, comprising aconduit extending from the lower end of the assembly upward toward theupper end of the same; a displacement means near the lower end of theassembly; means for supplying gas under pressure for the functioning ofthe displacement means; valves adapted to admit gas from the said meansfor supplying gas into the displacement means, for discharging gas fromthe displacement means into the gas-discharge-line, for admitting liquidfrom the well into the displacement means, and for' discharging liquidfrom the displacement means into one of the conduits above named; valvemeans for discharging gas from the gasdischarge-line; means foractuating and timing the valves aforesaid in a manner to cause thedisplacement means and the valves to co-act to cause the displacementmeans to draw liquid from the well and to discharge the same into one ofthe conduits first above named; means for maintaining flow of fluid intothe upper end of one of the conduits first above mentioned and outwardfrom the other of the said conduits; and means for discharging increaseof fluid at the upper end of the assembly of strings of tubing.

5. In apparatus for pumping wells, strings of tubing installed in' awell and forming two conduits for the conveyance of fluid between theupper and the lower ends of the strings of tubing; a displacement meansat the lower end of the two conduits and a gas-discharge-line extendingfrom the displacement means upward toward the upper end of the conduits;valve means for permitting flow of fluidfrom the gas-discharge-line intoone of the two conduits but not in the reverse direction; means forsupplying gas under pressure to the displacement means; valve meansadapted to admit gas from the means of sup plying gas to thedisplacement means, to discharge gas from the displacement means intothe gas-discharge-line, to exhaust gas from the displacement means, toadmit liquid from the well into the displacement means, and to dischargeliquid from the displacement means into one of the two conduits firstabove named, the said valve means being adapted to be actuated and timedin the sequence required to cause the displacement means and the saidvalves to co-act to draw liquid from the well and discharge liquid intoone of the two conduits aforesaid; and means for discharging increase offluid at the upper end of the conduits.

6. In apparatus for pumping wells, strings of tubing, installed in awell; connecting means adapted to provide, in combination with the saidstrings of tubing, conduits for the conveyance of a descending flow offluid from the upper end of the strings of tubing to the lower ends ofthe same and an ascending flow of fluid from the lower end to the upperend; a displacement means near the lower end of the strings of tubing;means for supplying gas under pressure for the functioning of thedisplacement means as described; a gas-discharge-line, comprising astring of tubing extending from a connection with the displacement meansupward toward the ground surface; valve means adapted to admit gas tothe displacement means, to discharge gas into the gas-dlscharge-line, toadmit liquid from the well into the displacement means, and to dischargeliquid from the displacement means into the aforesaid conduit conveyingthe ascending flow of fluid; valve means for discharging gas from thegas-discharge-line into one of the conduits aforesaid at a point abovethe displacement means having a pressure within the conduit very muchless than the pressure in the displacement means, the valve means beingadapted to prevent flow in the reverse direction; means for actuatingand timing the said valve means in a manner to cause the displacementmeans and the valve means to co-act to cause the displacement means andthe valve means to draw liquid from the well and to discharge the sameinto the aforesaid conduit conveying the ascending flow of fluid; andmeans for maintaining a flow of fluid downward to the lower end of thestrings of tubing through one of the conduits and back to the upper endin another conduit and discharging increase of fluid at the groundlevel.

7. In apparatus for pumping wells, strings of tubing, in concentricassembly, installed in a well; means for communicating between thestrings of tubing at their lower ends, forming means for conveying fluiddownward through a passageway from the upper end to the lower end of theassembly and a flow of fluid in the upward direction in anotherpassageway; displacement means connected to the strings of tubing at thelower end of the assembly; means for supplying and conveying gas underpressure to the displacement means; valve means for admitting gas to thedisplacement means and for exhausting gas from the same in sequence asrequired for the alternate filling and emptying of the displacementmeans, the gas thus used being exhausted into the aforesaid passagewayfor conveying fluid in the upward direction at a point far enough abovethe displacement means and the lower end of the assembly of tubing forthe pressure in the passageway last named to be sufliciently lower thanthe pressure in the displacement means to provide a substantialoperating power head for the displacement means; valve means foradmitting liquid from the well into the displacement means and fordischarging fluid from the displacement means into the aforesaidpassageway conveying fluid in an upward direction, the valve means beingadapted to prevent flow in the reverse direction; means for maintainingand regulating the flow of fluid into the upper end of the aforesaidpassageway conveying fluid in the downward direction; and means fordischarging and regulating the flow of fluid out of the passagewaycarrying the upward flow of fluid and withdrawing increase of fluid.

8. In apparatus for pumping wells, strings of tubing, assembled in awell; means of communication between the strings of tubing at the upperand lower ends thereof and forming in combination therewith, means forconveying a flow of fluid downward from the upper end of the assembly tothe lower end of the same in one conduit and a flow of fluid upward fromthe lower end to the upper end in another conduit; a displacement meansat the lower end of the assembly; a

means for supplying gas under pressure to the displacement means throughone of the conduits aforesaid; means for exhausting gas from thedisplacement means upward to a point at a distance above thedisplacement ,means including means for discharging gas into one of theconduits aforesaid, the pressure atthe point of discharge being verymuch lower than the pressure at the lower end of the conduit last namedat any time, the

valve means being adapted to prevent flow in the reverse direction;valve means adapted to admit gas from the means for supplying gas to thedisplacement means, to discharge gas from the displacement means intothe means for exhausting gas aforesaid, to admit fluid from the wellinto the displacement means, and to discharge fluid from thedisplacement means into the aforesaid conduit for conveying an upwardflow of fluid, the said valve means being adapted to be actuated andtimed to operate in the sequence necessary to cause the displacementmeans and the said valve means to coact to draw fluid from the well anddischarge the same into the aforesaid conduit for conveying an upwardflow of fluid; and means for maintaining and regulating the flow offluid in the conduits aforesaid at their upper ends and dischargingincrease of fluid.

9. In apparatus for pumping wells, strings of tubing installed in awell; means of communica-, tion between the strings of tubing formingtherewith conduits for conveying fluid downward through one conduit tothe lower end of the strings of tubing and for conveying fluid upwardthrough another conduit from the lower end to the point of beginning; adisplacement means connected to the strings'of tubing at the lower end;means for supplying gas under pressure to the displacement means; meansfor admitting gas to the displacement means and for exhausting gas fromthe same, the means of exhausting gas including means for conveying theexhaust gas to a point at a distance above the displacement means andinjecting the gas into the aforesaid conduit conveying an upward flow offluid at a point at such'a distance above that the pressure in the saidconduit is very much less than the pressure at the lower end of the sameconduit; valve means for admitting fluid from the well into thedisplacement means and for discharging fluid from the displacement meansinto one of the conduits aforesaid; the valve means being adapted toprevent flow in the reverse direction; means for actuating the valvemeans; and means for discharging fluid at the upper end of the stringsof tubing.

H. W. DOUBRAVA. IRVING C. HARRIS.

